1. Technical Field
The present invention relates to a fabrication apparatus and fabrication method of a semiconductor device, particularly a fabrication apparatus and fabrication method of a semiconductor device produced by heating a substrate.
2. Description of Related Art
In the fabrication of semiconductor devices such as optical devices and electronic devices, a semiconductor substrate is generally heated in a chamber (reaction chamber), followed by execution of various chemical and physical processing during the heating. For example, formation of an epitaxial film on a substrate is carried out by supplying material gas into the chamber and growing a film epitaxially, based on the material gas component, on the surface of the heated substrate. In this case, it is important to reduce the temperature distribution of the substrate in the chamber in order to grow a film of high quality uniformly on the substrate. In other words, rendering the temperature distribution of the substrate uniform is critical to ensure the reliability and quality of the semiconductor device, in addition to improving the yield.
Various approaches are conventionally proposed to render the substrate temperature distribution uniform. For example, WO 2003/096396 discloses the approach of suppressing a temperature gradient that will be developed at a substrate during high-temperature processes by suspending a substrate on a support structure having a specified height, made from a material having a relatively low thermal conductivity, located on a susceptor.
According to the technique disclosed in WO2003/096396, the thermal flux through the support structure tends to become greater than the thermal flux through the gas at the gap between the substrate and the susceptor. Accordingly, the temperature of the substrate at the region in contact with the annular support structure increases. As a result, the temperature of the substrate will be high at the outer peripheral region and low at the central region, leading to the problem that a temperature distribution is readily developed.